I was alone in the office elevator. Then the doors flew open, and in walked our CEO. It was early in my career, and I was new and had never met him—but I recognized him right away. In fact, I'd been hired to write his speeches.

So this was quite an opportunity. All I had to do was extend my hand, introduce myself, and tell him I was delighted to have been hired to write for him. I could even have suggested a meeting! And I'm sure he would have agreed—what CEO wouldn't want to get to know his new speechwriter?

But of course, I blew it.

I didn’t think quickly enough, and all we did was exchange a short nod. In fact, over the next two years, I would never meet him face to face again. Ultimately, I left the company because, well, who wants to write for someone she has no access to? It might've been different if I had just said hello.

It's offhand moments like these that offer big opportunities to build relationships with executives who otherwise might be out of reach—especially to young staff or new hires. Chances are you already have a good rapport with your own boss—you work together every day. It's the people higher up who may seem much further away—until you're suddenly stuck with them inside an elevator, the modern office's great equalizer.

Here's what to do when that happens.

READ THE (VERY TINY) ROOM

An elevator is a room of sorts. So first, decide whether you have a real opportunity. If there are others in the elevator, it’s probably not the best time to strike up a chat about a big topic with a senior-level exec. It's not that there'd be anything inherently wrong with that, but the situation just might not be right, and it could turn out awkward for both of you.

Rightly or wrongly, others may see you as breaking rank or overstepping your boundaries. Or the executive might just be caught off guard and feel embarrassed. So save your elevator conversations for moments when the two of you are riding alone.

Even in that one-on-one situation, keep your office-politics antenna out. If your boss’s boss is deep in thought, leave her alone. She may be thinking through her next meeting or hashing out a tricky decision. Make eye contact if you can, and show that you're respectfully aware of her presence and status, but otherwise keep to yourself. Another time will come!

SAY SOMETHING SIGNIFICANT

If the situation does seem right, speak with substance and avoid trivial exchanges. Don’t waste your chance asking whether she had a nice weekend or what she thinks of the weather. Go for something more substantial—an observation or question that has the subtle power to leave a strong impression and, ultimately, move your career forward.

After all, if you don't think big, what's the point? Here are a few ways to do that while keeping it casual:

Introduce yourself. If you haven't met the executive before, extend your hand and say, "Hi, I’m Henry Yarmouth, the director of our call center." You might also add something that shows your commitment to the company, as long as it doesn't sound like you're sucking up, like, "I started in August and so far really like it. The people are great."

Share a win. Tell the executive about something you or your team have accomplished. A diversity manager told me that she rides the elevator regularly with her CEO, since they both have offices on the 20th floor. Just about every time, she takes the opportunity to highlight how she and her team are helping the business. In a recent elevator ride, she shared with the CEO about how her team won a contract to support new immigrants. Don’t worry about sounding boastful! It's a short ride, so make a quick, positive impact. Your executive will appreciate the good news.

Offer your congratulations. You can also congratulate your boss’s boss on an achievement, either his own, his department’s, or the company’s. If you saw him give a talk recently, don't just say you liked it, explain why. If his department received an honor, mention that. If Q4 results were impressive, comment on that. People love to be recognized for success, and if you stay current with this sort of information—as you should—you'll put a glow on the executive’s face.

Ask for a meeting. What better elevator topic is there than a request to meet? I know of a director who reported to a VP but was so savvy that he requested meetings with the SVP. And when the VP left, that director was promoted to the VP role. In order for that to happen, of course, the SVP needed to know who he was. So seize your chance in the elevator to say something like, "I’m working on some employee engagement issues, and I’d love to hear your perspective. Any chance I'd be able to steal a half hour of your time?" Who wouldn’t be flattered by such a request? Just make sure you let your own boss know—you don't want to be seen as going over her head.

FOLLOW UP

Finally, follow up on whatever conversation you do manage to strike up. You might schedule a quick meeting or write an email that expands on your comments. Or you might share an article that came to mind based on what you discussed. You can even invite that executive to speak to your team. The important thing is to continue building that relationship. Eventually your efforts will reap great returns.

And remember: The elevator conversation is far more than a chat inside a moving box of metal. You can apply this advice to all the informal situations where you have a short slice of time to strike up a rapport with senior executives. It might be a chance encounter in a corridor, a coffee room, the kitchenette, or a networking event. But wherever that brief meeting occurs, go for it! Put yourself forward. Those who get noticed, get promoted.